FIG. 13 illustrates a conventionally configured moving type radiation device. In this device, a radiation source 56 configured to irradiate radiation and a support column 52 supporting the radiation source 56 and extending in a vertical direction are provided on a hand-truck carriage. The support column 52 slidably supports the radiation source 56. The radiation source 56 is configured to be moved in the vertical direction while being supported by the support column 52. Such a device is electrically assisted, and is devised so that the operator can move easily without applying a strong force by hands.
Such a moving type radiation device can be moved to a subject's room. By using this device, it becomes possible to perform radiation imaging of the subject without moving the subject as much as possible.
FIG. 14 illustrates a mechanism for raising and lowering the radiation source 56. As shown on the left side of FIG. 14, the radiation source 56 is supported by a mechanism composed of a tip support column 54, an intermediate member 53, and a support column 52 connected with each other. When a force is applied so as to move the radiation source 56 upward and downward, the tip support column 54, the intermediate member 53, and the support column 52 move upward and downward in conjunction with the force.
One example for realizing such movement is a so-called well bucket type mechanism shown on the left side of FIG. 14 which is composed of a fixed pulley provided in the intermediate member 53. When the radiation source 56 is tried to move downward, the fixed pulley rotates counterclockwise, and the wire is wound up to the left side. As a result, the radiation source 56 moves downward. The intermediate member 53 itself also moves downward while being differentiated from the radiation source 56 although the moving speed is not as fast as that of the radiation source 56. Hereinafter, this moving speed will be addressed.
The right side of FIG. 14 illustrates a diagram used for considering how fast the radiation source 56 and the intermediate member 53 move when the radiation source 56 is moved downward. When the radiation source 56 is moved downward, the radiation source 56 and the intermediate member 53 move relatively. It is assumed that the speed at this time is, for example, 0.1 m/s. The wire is wound up to the left side of the fixed pulley at this speed.
When the radiation source 56 is moved downward, the intermediate member 53 and the support column 52 move relatively. The speed at this time is 0.1 m/s. This is because that the wire will be wound up from the right side of the fixed pulley at this speed. That is, the radiation source 56 moves downward at the speed of 0.2 m/s with reference to the support column 52. That is, according to this mechanism, as shown in FIG. 15, the radiation source 56 moves at twice the speed of the intermediate member 53.